- N-Functionalised Imidazoles as Stabilisers for Metal Nanoparticles in Catalysis and Anion Binding
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Metal nanoparticles (NPs) have physicochemical properties which are distinct from both the bulk and molecular metal species, and provide opportunities in fields such as catalysis and sensing. NPs typically require protection of their surface to impede aggregation, but these coatings can also block access to the surface which would be required to take advantage of their unusual properties. Here, we show that alkyl imidazoles can stabilise Pd, Pt, Au, and Ag NPs, and delineate the limits of their synthesis. These ligands provide an intermediate level of surface protection, for which we demonstrate proof-of-principle in catalysis and anion binding.
- Beer, Paul D.,Cookson, James,Serpell, Christopher J.
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p. 683 - 690
(2020/07/03)
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- Selective hydrogenation of nitroarenes under mild conditions by the optimization of active sites in a well defined Co?NC catalyst
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The catalytic hydrogenation of aromatic nitro compounds containing multiple functional groups into amino compounds with high conversion rates, selectivity, and stability under mild conditions is a great challenge. Herein, a well defined catalyst (Co?NC) is prepared through the pyrolysis of the Co-centered metal-organic framework (MOF) at the optimized temperature. The as-synthesized catalyst exhibits a high conversion rate and selectivity for the hydrogenation of 12 aromatic nitro compounds with different competing groups into desired amino compounds with hydrazine hydrate under mild conditions (80 °C, 30 min, and 1 atm). The catalyst also shows excellent stability and can be reused over 20 times without considerably losing its activity. It is found that the Co-Nx site is the main active site for catalytic hydrogenation, and the Mott-Schottky effect between the surface Co NPs and N-doped carbon can further promote the hydrogenation reaction. EXAFS, TEM, XPS, and Raman analyses confirm that cobalt nanoparticles (NPs) are properly encapsulated by the N-doped carbon matrix at the optimized temperature, and the Co species maintain a high spin state after the catalysis, which may be responsible for the high performance of Co?NC. This work demonstrates not only a highly efficient catalyst for hydrogenation under mild conditions, but also provides insight into the active sites in Co-based catalysts for hydrogenation.
- Chen, Shuo,Jiang, Hong,Jiang, Shun-Feng,Ling, Li-Li
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p. 5730 - 5741
(2020/09/21)
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- Site-Selective Copper-Catalyzed Amination and Azidation of Arenes and Heteroarenes via Deprotonative Zincation
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Arene amination is achieved by site-selective C-H zincation followed by copper-catalyzed coupling with O-benzoylhydroxylamines under mild conditions. Key to this success is ortho-zincation mediated by lithium amidodiethylzincate base that is effective for a wide range of arenes, including nonactivated arenes bearing simple functionalities such as fluoride, chloride, ester, amide, ether, nitrile, and trifluoromethyl groups as well as heteroarenes including indole, thiophene, pyridine, and isoquinoline. An analogous C-H azidation is also accomplished using azidoiodinane for direct introduction of a useful azide group onto a broad scope of arenes and heteroarenes. These new transformations offer rapid access to valuable and diverse chemical space of aminoarenes. Their broad applications in organic synthesis and drug discovery are demonstrated in the synthesis of novel analogues of natural product (-)-nicotine and antidepressant sertraline by late-stage amination and azidation reactions.
- Hendrick, Charles E.,Bitting, Katie J.,Cho, Seoyoung,Wang, Qiu
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p. 11622 - 11628
(2017/08/30)
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- Perovskite-type ferromagnetic BiFeO3 nanopowder: A new magnetically recoverable heterogeneous nanocatalyst for efficient and selective transfer hydrogenation of aromatic nitro compounds into aromatic amines under microwave heating
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Perovskite-type ferromagnetic BiFeO3 nanopowder was readily synthesized via thermal decomposition of Bi[Fe(CN)6].5H2O complex and characterized using thermal analysis (TGA/DSC), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), magnetic measurement and Brunauer-Emmett- Teller (BET) specific surface area measurements. The magnetic measurements show a ferromagnetic behavior for the BiFeO3 nanoparticles at room temperature. This nanosized ferromagnetic oxide with an average particle size of approximately 20 nm and a specific surface area of 48.5 m2/g was used as a new magnetically recoverable heterogeneous nanocatalyst for the highly efficient and selective reduction of aromatic nitro compounds into their corresponding amines by using propan-2-ol as the hydrogen donor under microwave irradiation. This method is regio- and chemoselective, clean, inexpensive and compatible with the substrates having hydrogenlyzable or reducible functional groups. As compared with conventional heating, this method is very fast and suitable for the large-scale preparation of different substituted anilines as well as other arylamines. The catalyst can also be reused without loss of activity. Iranian Chemical Society 2012.
- Farhadi,Rashidi
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p. 1021 - 1031
(2013/02/23)
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- Novel approach for the synthesis of N-Substituted pyrroles starting directly from nitro compounds in water
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A novel approach for a facile high-yielding synthesis of N-substituted pyrroles has been discovered by the treatment of nitroarenes with 2,5-dimethoxytetrahydrofuran using indium in dilute aqueous HCl at room temperature. Taylor & Francis Group, LLC.
- Das, Biswanath,Shinde, Digambar Balaji,Kanth, Boddu Shashi,Kumar, Jayprakash Narayan
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experimental part
p. 548 - 553
(2011/11/29)
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- Approaches to the synthesis of 2,3-dihaloanilines. Useful precursors of 4-functionalized-1 H-indoles
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2,3-Dihaloanilines have been proved as useful starting materials for synthesizing 4-halo-1H-indoles. Subsequent or in situ functionalization of the prepared haloindoles allows the access to a wide variety of 2,4- or 2,3,4-regioselectively functionalized indoles in good overall yields. As no efficient synthetic routes to 2,3-dihaloanilines have been described in the literature, different approaches to the preparation of these 1,2,3-functionalized aromatic precursors are now presented. The most general one involves a Smiles rearrangement from the corresponding 2,3-dihalophenols and allows the preparation of 2,3-dihaloanilides in a straightforward and synthetically useful manner.
- Guilarte, Veronica,Castroviejo, M. Pilar,Garcia-Garcia, Patricia,Fernandez-Rodriguez, Manuel A.,Sanz, Roberto
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experimental part
p. 3416 - 3437
(2011/06/28)
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- NiO nanoparticles prepared via thermal decomposition of the bis(dimethylglyoximato)nickel(II) complex: A novel reusable heterogeneous catalyst for fast and efficient microwave-assisted reduction of nitroarenes with ethanol
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NiO nanoparticles with an average size of 12 nm and a high specific surface area of 88.5 m2/g were easily prepared via the thermal decomposition of the complex Ni(dmgH)2 and were characterized by TGA, XRD, FT-IR, TEM and BET surface area measurement. This nanosized transition metal oxide was used as a new heterogeneous catalyst for the reduction of nitroarenes under microwave irradiation. The efficient and selective reduction of aromatic nitro compounds into their corresponding amines was observed by using ethanol as a hydrogen donor (reducing agent) and KOH as a promoter under microwave irradiation. This highly regio-and chemoselective method is fast, simple, inexpensive, high yielding, clean and compatible with several sensitive functionalities, such as halogens,-OH,-OCH3,-CHO,-COCH 3,-COOH,-COOEt,-CONH2,-CN,-CHCH2 and-NHCOCH3. This method is suitable for the large scale preparation of different substituted anilines as well as other arylamines. In addition, the catalytic activity of nanosized NiO is higher than that of the bulk sample.
- Farhadi, Saeid,Kazem, Maryam,Siadatnasab, Firouzeh
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scheme or table
p. 606 - 613
(2011/04/16)
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- Perovskite-type LaFeO3 nanoparticles prepared by thermal decomposition of the La[Fe(CN)6]·5H2O complex: A new reusable catalyst for rapid and efficient reduction of aromatic nitro compounds to arylamines with propan-2-ol under microwave irradiation
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Perovskite-type LaFeO3 nanoparticles were readily synthesized via thermal decomposition of the La[Fe(CN)6]·5H2O complex and characterized by using thermal analysis (TGA), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and BET specific surface area measurement. This nanosized perovskite-type oxide with an average particle size of 35 nm and a specific surface area 38.5 m2/g was used as a new reusable heterogeneous catalyst for highly efficient and selective reduction of aromatic nitro compounds into their corresponding amines by using propan-2-ol as the hydrogen donor under microwave irradiation. This method is regio- and chemoselective, clean, inexpensive and compatible with the substrates having hydrogenlysable or reducible functional groups. As compared with conventional heating, this method is very fast and suitable for large scale preparation of different substituted anilines as well as other arylamines. The catalyst can also be reused without observable loss of its activity.
- Farhadi, Saeid,Siadatnasab, Firouzeh
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experimental part
p. 108 - 116
(2011/05/19)
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- Microwave-assisted rapid and efficient reduction of aromatic nitro compounds to amines with propan-2-ol over Nanosized perovskite-type SmFeO 3 powder as a new recyclable heterogeneous catalyst
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Nanosized perovskite-type SmFeO3 powder, prepared through the thermal decomposition of Sm[Fe(CN)6].4H2O with an average particle diameter of 28 nm and a specific surface area of 42 m2 g-1, was used as a recyclable heterogeneous catalyst for the efficient and selective reduction of aromatic nitro compounds into the corresponding amines by using propan-2-ol as a hydrogen donor (reducing agent) and KOH as a promoter under microwave irradiation. This highly regio-and chemoselective catalytic method is fast, clean, inexpensive, high yielding and also compatible with the substrates containing easily reducible functional groups. In addition, the nanosized SmFeO3 catalyst can be reused without loss of activity.
- Farhadi, Saeid,Siadatnasab, Firouzeh,Kazem, Maryam
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experimental part
p. 104 - 108
(2011/06/27)
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- Hydrous zirconia supported iridium nanoparticles: An excellent catalyst for the hydrogenation of haloaromatic nitro compounds
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Ir/ZrO2·xH2O was prepared by co-precipitation and characterized by TEM, XRD, and XPS. It showed an excellent catalytic performance for the hydrogenation of haloaromatic nitro compounds to the corresponding amines in the mixture solvent of ethanol and water. The catalyst gave both conversion and selectivity to be over 99.9% for the hydrogenation of p-chloronitrobenzene to p-chloroaniline. Besides the intrinsic characterization of iridium in the hydrogenation of haloaromatic nitro compounds, the high activity and selectivity of Ir/ZrO2·xH2O is probably attributed to the formation of hydrogen bond between substrate and the hydroxyl groups on the surface of the hydrous catalyst or solvent water to activate the N{double bond, long}O bond in nitro group. The activated N{double bond, long}O bond is easy to be attacked by the activated hydrogen, so the hydrogenation is promoted.
- Fan, Guang-Yin,Zhang, Lei,Fu, Hai-Yan,Yuan, Mao-Lin,Li, Rui-Xiang,Chen, Hua,Li, Xian-Jun
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scheme or table
p. 451 - 455
(2010/11/21)
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- Chemoselective reduction of aromatic nitro and azo compounds in ionic liquids using zinc and ammonium salts
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Nitroarenes were chemoselectively reduced to the corresponding amines using zinc and aqueous ammonium salts in ionic liquids as a safe and recyclable reaction medium. Our results specify the effect of ammonium salts in the process; the combination of Zn/NH4Cl in [bmim][PF6] or Zn/HCO2NH4 in [bmim][BF4] were the suitable conditions for the reduction of nitroarenes. Azobenzenes were also smoothly reduced to hydrazobenzenes with Zn/HCO2NH4 (aq.) in recyclable [bmim][BF4] without any over reduction to the corresponding anilines.
- Khan, Faiz Ahmed,Dash, Jyotirmayee,Sudheer,Gupta, Rakesh Kumar
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p. 7783 - 7787
(2007/10/03)
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- Process for the preparation of 6-(2,3-dichlorophenyl)-1,2,4-triazine-3,5-diamine, commonly known as lamotrigine
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A process for the preparation of 6-(2,3-dichlorophenyl)-1,2,4-triazine-3-5-diamine (lamotrigine) of the formula I: 2,3-Dichloronitrobenzene in C1-C6aliphatic alkanol is hydrogenated at 55-90 psi gas pressure using metal catalyst at 27-35° C. 2,3-Dichloroaniline is diazotised and cyano-de-diazonised with metal cyanide at 65-80° C. 2,3-Dichlorobenzonitrile is hydrolysed and 2,3-dichlorobenzoic acid is chlorinated at 55-130° C. Cyano-de-halogenation of 2,3-dichlorobenzoyl chloride is carried out with a metal cyanide and alkali metal iodide by refluxing in an aprotic solvent under an inert atmosphere. 2,3-Dichlorobenzoyl cyanide is condensed with aminoguanidine bicarbonate in an organic solvent in acidic conditions using catalyst at 90-125° C. followed by insitu cyclisation of the Schiff's base by refluxing in an aliphatic alkanol with base. Crude lamotrigine is purified.
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Page/Page column 7
(2010/01/31)
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- Regioselective dechlorination of 2,3-dichloronitrobenzene into 3-chloronitrobenzene and regioselective dechlorination-hydrogenation into 3-chloroaniline
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Tetrakis(triphenylphosphine)palladium, Pd(PPh3)4, is an efficient catalyst for the selective dechlorination of 2,3-dichloronitrobenzene into 3-chloronitrobenzene. During the reaction the selectivity is over 90% in a very reproducible manner and the reaction can be stopped at the maximum selectivity. Pd(PPh3)4 is also a catalyst for the one-pot transformation of 2,3-dichloronitrobenzene into 3-chloroaniline (selectivity >60%).
- Angeloff, Ariane,Brunet, Jean-Jacques,Legars, Pierre,Neibecker, Denis,Souyri, Denis
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p. 2301 - 2303
(2007/10/03)
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- SELECTIVE AND SEQUENTIAL REDUCTION OF NITROAROATICS BY MONTMORILLONITESILYLAMINEPALLADIUM(II) COMPLEX
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Nitroaromatics are sequently and selectively hydrogenated in quantitative yields at room temperature and atmospheric pressure by interlamellarmontmorillonitepalladium(II) complex, a heterogenised homogenous catalyst.
- Mukkanti, K.,Rao, Y. V. Subba,Choudary, B. M.
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p. 251 - 252
(2007/10/02)
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- Novel Reactions: Part I - Facile Synthesis of Substituted ortho-Chloranilines from Nitrobenzene Derivatives
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N-Substituted benzo and acetohydroxamic acids (5), prepared from N-arylhydroxylamines and benzoyl or acetyl chloride, react readily with thionyl chloride at low temperature to give ortho-chloroanilide derivatives (6) in good yield.The latter (6) on hydrolysis give ortho-chloroanilines (10).Since the N-arylhydroxylamines are obtained from nitroarenes by partial reduction, the overall reaction amounts to the preparation of 10 from nitroarenes.
- Ayyangar, N. R.,Kalkote, U. R.,Nikrad, P. V.
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p. 872 - 877
(2007/10/02)
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- Hydrogenation of halogen-substituted aromatic nitro compounds
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This invention relates to the hydrogenation of halogen-substituted aromatic nitro compounds and in particular provides a novel catalyst for use in such processes. In more detail a catalyst suitable for use in the hydrogenation of halogen-substituted aromatic nitro compounds substantially without simultaneous dehalogenation comprises one or more metals from the group consisting of platinum, palladium, rhodium, iridium, ruthenium and osmium supported on or impregnated into a carrier material comprising carbon activated with phosphoric acid or a salt thereof.
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